Various types of known gas and smoke detectors incorporate optical elements. These could include lenses or reflectors, which are used to direct or focus light relative to a sensing element, for example, a photo diode or other form of opto/electrical converter. Such optical components are recognized as being useful and appropriate in that they can provide improved performance and reduced size in such detectors. However, they are susceptible to airborne water vapor which can condense on and deteriorate their performance.
It is recognized that condensation can occur on optical surfaces which are colder relative to warmer incoming humidity carrying ambient air. The difference in temperature results in the airborne water vapor condensing on the optical surfaces.
In many instances, the condensation is particularly likely to occur if the detector is carried from a colder environmental condition to a warmer environmental condition. This is especially an issue if the warmer ambient air is higher in humidity.
It has been known to continually heat optical surfaces in such detectors to maintain their temperature above the dew point. In known detectors, the heating process is carried out continuously. This requires, of course, supplying a certain amount of electrical energy continuously to the detector only for the purpose of heating the respective optical components.
There continues to be a need for detectors which require lower average power, while still carrying out an appropriate heating function of relevant optical components, then now available. Additionally, it would be desirable to be able to improve battery life and to decrease the power requirements of any wiring which is used to interconnect pluralities of detectors with a common power supply and a remote system. Preferably such improved operating efficiency could be achieved without substantially increasing component costs, manufacturing costs, or complexity of such detectors.